First things first. For those of you who swear by the pink dress, yes, there’s a version for you as well:
…Aaaaand moving on. So Prince Philip does specifically and emphatically say “this is the 14th century!” at some point during the film, but Philip’s an idiot (a handsome, handsome idiot) and I, never afraid to ignore source material, ignored him.
Oddly enough Philip’s clothing is a better point of reference than Aurora’s (since the hourglass, off-the-shoulder cut of her dress is straight out of the 1950’s), and there are far more examples of his get-up from the 1460’s onward than in the 14th century. I went with my gut and ended up with something around 1485- a little later than one might expect, but it’s such a (beautifully) stylized film that all bets are off.